Tyndall National Institute - Conference Items

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    Optical communication for next generation chip on tip surgical endoscopes
    (Society of Photo‑Optical Instrumentation Engineers (SPIE), 2024-03-12) Khan, Asif Newaz; Antony, Cleitus; Baskaran, Meena; Corbett, Brian; Konugolu Venkata Sekar, Sanathana ; Burke, Ray; Andersson-Engels, Stefan; Townsend, Paul D.; Marcu, Laura; van Soest, Gijs; Bourantas, Christos; Science Foundation Ireland
    The next-generation chip-on-tip surgical endoscopes require small footprint (1-3 French), hyperspectral imaging capability for multi-biomarker quantification with high frame rate to reduce motion artefacts. These innovations demand high data rate links, which could require twisted-pair cables if transmitted electrically. To eliminate bulky electrical wiring, we propose an all-optical powering and communication chip at the distal end consisting of a monolithically series interconnected Photonic Power Converter and a reflective electroabsorption modulator (REAM) based on a p-i-n diode structure with an embedded multiple quantum well (MQW) absorber. Optical sources for the power generator and reflective modulator are provided remotely over optical fiber, thus removing the need to host power-hungry lasers at the distal tip. To simplify the overall design, the communication scheme takes advantage of the REAM’s dual functionality as a modulator and detector. Here, we have used a commercial REAM designed to operate at 1550nm and a novel Time Division Duplexing (TDD) communication protocol to demonstrate bidirectional transmission at 500 Mb/s over a single-mode fiber on a benchtop in order to examine the feasibility of the scheme. We found that at shorter wavelength near the MQW band-edge, zero-bias operation of the REAM is possible and the required modulation voltage swing is reduced. Operating under zero-bias at 1520nm instead of 1550nm leads to negligible static energy consumption and about 47% reduction in dynamic energy consumption, reaching an 8dB extinction ratio. Additionally, at 1520nm, the photocurrent generation responsivity increases dramatically at zero-bias, allowing the Transimpedance Amplifier (TIA) to be removed from the receiver circuit. This results in reduced footprint and power consumption of the receiver front end circuit.
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    Electrically active defects in Al2O3-InGaAs MOS stacks at cryogenic temperatures
    (Institute of Electrical and Electronics Engineers (IEEE), 2024-03-27) La Torraca, Paolo; Padovani, Andrea; Wernersson, Lars-Erik; Cherkaoui, Karim; Hurley, Paul; Larcher, Luca; Horizon 2020
    The effects of defects in In 0.47 Ga 0.53 As/Al 2 O 3 /Ni metal-oxide-semiconductor (MOS) stacks at cryogenic temperatures are investigated. The MOS stacks exhibit a hysteresis in the capacitance-voltage (CV) curve, both at room temperature and at 100K, indicating the presence of effective charge capture/emission dynamics in the oxide even at cryogenic temperatures. Border traps (BTs) in the Al 2 O 3 close to the In 0.47 Ga 0.53 As/Al 2 O 3 interface are recognized as the best candidate for explaining the experimental CV. The hysteresis shape and its temperature dependence are used to profile the oxide defects’ properties, which allow correctly predicting the MOS stacks CV and conductance-voltage (GV) frequency dispersions and gaining insights on the hysteresis dynamics.
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    Towards a flexible polarimetric camera-on-tip miniature endoscope for 3x3 Mueller matrix measurements of biological tissue
    (Society of Photo-Optical Instrumentation Engineers (SPIE), 2023-08-11) Niemitz, Lorenzo; Sorensen, Simon T.; Wang, Yineng; Messina, Walter; Burke, Ray; Andersson-Engels, Stefan; Lilge, Lothar D.; Huang, Zhiwei; Science Foundation Ireland
    The interrogation of polarisation state of light is a developing technique in biomedical imaging. As polarised light interacts with structural changes in tissue, it has seen use in differentiation between (pre)cancerous and noncancerous tissue, for example. In biomedical imaging rapid diagnostics using minimally invasive techniques is desirable. Endoscopy is already very prevalent in medicine and therefore miniaturisation of polarimetry systems onto endoscopic platforms is a natural development. Flexibility of such a device allows navigation to more complicated parts of the body. All polarimetric systems consist of a polarisation state generator (PSG) and a polarisation state analyser (PSA) which need to be integrated into such a system. A rigid endoscope capable of imaging a full 4×4 Mueller matrix has been developed by Qi et al. This endoscope achieves the polarisation state generation a rigid rotating sheath. Partial polarimetric endoscopy which captures a 3×3 Mueller matrix has also been demonstrated and is easier to achieve since it does not require quarter wave plates in the generator or analyser. Clancy et al and Qi et al both demonstrate a rigid polarimetric endoscopy using a stereo endoscope and a standard rigid endoscopy, respectively. Integration of polarisation state analyser and generator into the tip has been demonstrated using complex mechanical designs. However questions have been raised regarding the electromagnetic compatibility of such a system due to the presence of motors in the tip. Forward et al present a flexible 3×3 fibre based probe that uses diced polarisers orientated at the horizontal, vertical, and -45 degree positions to generate and acquire the necessary polarisation states. This work presents an imaging probe designed to enable in-vivo polarimetry measurements using a micro camera on the tip as a sensor. A 3×3 Mueller matrix image of crossed linear polarisers, captured using a micro camera is demonstrated. This device demonstrates the potential of micro camera sensors in providing 2-dimensional polarimetry data in a flexible endoscopic system. For a device to be used in a clinical setting it needs to be capable of providing data rapidly when it is needed, as well as being navigable to the target location. A fibre optically illuminated endoscope with micro-camera sensor allows for rapid switching of illumination fibres using backend illumination systems as well as rapid acquisition of data. Optical fibres enable the probe to be rigid or flexible depending on application, and the camera at the tip ensures consistent image quality regardless of application area. An idealised system and its potential future of polarimetry in translational biophotonic devices is also discussed.
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    Machine learning approaches for EM signature analysis in chipless RFID technology
    (Institute of Electrical and Electronics Engineers (IEEE), 2024) Rather, Nadeem; Simorangkir, Roy B. V. B.; Buckley, John L.; O’Flynn, Brendan; Tedesco, Salvatore; Science Foundation Ireland; Enterprise Ireland; European Regional Development Fund
    In this paper, for the first time, we provide a comprehensive review of Machine Learning (ML) approaches in Chipless Radio Frequency Identification (CRFID) technology, which is a fast-developing sector with applications in inventory management, anti-counterfeiting, health monitoring, and environmental monitoring, to name a few. ML techniques are rapidly being integrated to improve CRFID systems’ capabilities for robust detection of information. The combination of ML with CRFID technology is presented, examining various ML approaches, applications, challenges, and future perspectives. It is observed that ML has been successfully deployed in CRFID with high accuracy in the detection of information from CRFID tags. Challenges, such as data quality, security, and scalability are identified. Moreover, the literature currently struggles in the application of ML models on high-capacity tags, and lacks standardized data collection and sharing methodologies. We suggest the development of common data collection protocols, data sharing initiatives, and collaboration to establish a cohesive framework for CRFID data-driven research.
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    Adaptive neural network equalisation using skip connections for future 100 Gbit/s/λ passive optical networks
    (Institution of Engineering and Technology, 2023) Murphy, Stephen L.; Jamali, Fariba; Townsend, Paul D.; Antony, Cleitus; Science Foundation Ireland
    We present a novel equaliser based on a neural network with skip connections for 100 Gbit/s PAM4 SOA-preamplfied PONs which can converge within 2000 symbols on a burst-by-burst basis, and effectively compensate SOA patterning and 81.6 ps/nm fiber dispersion, enabling 21 dB system dynamic range.